This invention relates to thickness measuring and, more particularly, to a method and an apparatus based on the phenomenon of x-ray fluorescence for simultaneously measuring the thicknesses of the thin film components of a sample that comprises plural thin films deposited on top of each other on a substrate.
The measurement of coating thickness by x-ray fluorescence is widely practiced in industry. Thus, for example, x-ray fluorescence is often employed to measure the coating thickness of a tin-coated steel member. Moreover, the technique has been suggested for use in determining the thicknesses of both platings of a nickel/copper-plated steel member.
For some time, workers in the plating art have been attempting to simultaneously measure small-area portions of multiply plated structures. Such measurements are, for example, of importance in the fabrication of various microelectronic devices in which, for reasons of economy, only very small areas are to be plated with multiple layers that include an expensive metal such as gold. The ability to perform these measurements in a high-accuracy and high-speed way is an important factor in being able to carry out such fabrication processes in an economically attractive manner.